An outline of a conventional inverter apparatus will be roughly explained. The inverter apparatus is used to drive for example induction motor at a variable velocity with the commercial power source. Therefore, an inverter main circuit in the main body of the inverter apparatus includes a converter unit connected to the commercial power source, a rush-current-suppressing resistor, an inverter unit connected to the induction motor, and an inverter drive IC (hereinafter, “HVIC”) for controlling ON/OFF of a switching element of the inverter unit.
In the inverter main body, control power sources are additionally generated from the commercial power source. Specific examples of such control power sources are a control power source for controlling the HVIC and a control power source for controlling a relay for short-circuiting the rush-current-suppressing resistor, which are both provided in the inverter main circuit, a control power source for controlling an inverter control unit including a ROM and/or a microcomputer and a control power source for controlling an internal option including a microcomputer, which are both provided in the inverter main body, and a control power source for controlling a parameter unit including a microcomputer, which is provided outside the inverter main body.
In generating the control power sources, the commercial power-supply voltage is rectified and converted into a DC voltage in the inverter main body, a capacitor is then charged with this DC voltage, ON/OFF of the voltage charged in the capacitor is then controlled at a transistor, and the voltage subjected to the ON/OFF control is stepped down via a power transformer. As a result, various control power sources required are generated.
In the conventional inverter apparatus, various control power sources generated in the inverter main body are connected to the microcomputer and/or the peripheral circuit provided in the inverter apparatus including the inverter main body. Communications can thus be performed between the inverter control unit, the parameter unit, and the built-in option.
However, in the conventional inverter apparatus, the various control power sources are generated from the commercial power source in the inverter main body. Therefore, the commercial power source is required to be connected to the inverter main body even when a setting of the microcomputer and/or the peripheral circuit of the inverter apparatus is to be checked or changed with the control power sources, i.e., even when the inverter main circuit is not required to be driven. Therefore, electric power cannot be supplied to the microcomputer and/or the peripheral circuit, and communications cannot be established between the parameter unit and the built-in option when the inverter apparatus is out of order, or when the inverter apparatus is being moved, or when the inverter apparatus is being installed, i.e., when the commercial power source cannot be connected to the inverter main body. As a result, conventionally, the setting of the microcomputer and/or the peripheral circuit of the inverter apparatus cannot be checked or changed if the commercial power source cannot be connected to the inverter main body.
In Japanese Patent Application Laid-Open No. H11-146573 (FIG. 2) (hereinafter, “Patent Document 1”), an invention for reducing power consumption in a standby state of an electrical device is described. According to the invention of Patent Document 1, a microcomputer that controls electrical components is incorporated into a control board to which peripheral devices, such as a warm-water washing device, a warm toilet seat, and a remote control unit, are connected, and a main power source and an auxiliary power source connected to the commercial power source are connected to the microcomputer. When a power switch is off, the commercial power source and the main power source are disconnected from each other, and are in a standby state. In the standby state, electric power is continuously supplied only to the microcomputer by the auxiliary power source. After that, when the power switch is turned on, a signal is sent to the power source switch from the microcomputer, and the commercial power source and the main power source are reconnected to each other again. According to Patent Document 1, the power source is connected only to the microcomputer of the control board. Therefore, when the peripheral device is in the vicinity (e.g., a washing toilet), a serious problem does not occur. However, when the peripheral device is away from the microcomputer, the power source is connected only to the microcomputer, and hence the power source cannot be connected to the peripheral device, and the peripheral device may become inoperable. Additionally, according to Patent Document 1, the power source is not connected to the peripheral circuit unless the power of the commercial power source is supplied to the main power source, and hence, for example, information cannot be exchanged with the peripheral device.
In Japanese Patent Application Laid-Open No. 2000-92744 (FIG. 1) (hereinafter, Patent Document 2), an invention characterized in that, when an abnormality occurs in a power source system from which electric power is supplied to an option device side, only a driving power source to the option device is cut off to connect only a control power source. In other words, the voltage and current of the driving power source of the option device side are monitored, and, when an abnormality occurs therein, the power source system of the option device side is stopped, and, instead, the power of the option-device control system power source is supplied from the power source system of a main body side. Therefore, a power source for communication is there even if the driving power source is stopped, and, accordingly, communications is continuously performed between the main body and the option device. However, according to Patent Document 2, the commercial power source is always necessary for supplying electric power to the option device, and hence communications cannot be performed between the main body and the option if there is no commercial power source.
Therefore, it is an object of the present invention to provide an inverter apparatus in which, even when a commercial power source cannot be connected to an inverter apparatus or even when a control power source is cut off, a setting of a microcomputer of the inverter apparatus or a setting of a peripheral circuit of the inverter apparatus can be checked or changed.